<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style type="text/css">
        div{width:100px;
        height:100px;
        background-color:red;
        margin:20px;
        }
        /* #one{
            width:100px;
            height:100px;
            background-color:blue;
        } */
        /* .one{
            width:100px;
            height:100px;
            background-color:orange;
        }
        #one>div{
            
        } */
        /* #one+div{

        } */
        /* [id]{
            background-color: blue;
        } */
        /* [class="one"]{
            background-color:pink;
        }
        [class~="one"]{
            background-color:pink;
        } */
        /* [class^="o"]{
            background-color:pink;
        } */ 
        /* [class$="o"]{
            background-color:purple;
        } */ 
        div#one,div.two,ul{
            background-color: blue;
        }
    </style>
</head>
<body>
    <div id="one" class="one"></div>
    <div class="one two"></div>
    <div class="two"></div>
    <div id="four" class="one"></div>
    <div class="three"></div>
    <ul >
        <li>111
            <ul>1</ul>
        </li>
        <li>222
            <ul>2</ul>
        </li>
        <li>333
            <ul>3</ul>
        </li>
    </ul>
</body>
</html>